1. Field of the Invention
This invention relates to the fabrication of laminated transparencies and more particularly to the removal of excess interlayer material about the periphery of a laminated windshield.
2a. Technical Considerations
In a conventional laminated windshield fabrication operation, pairs of glass sheets are initially cut to shape and bent to a desired contour. A flexible, thermoplastic interlayer material, for example polyvinylbutyral, is inserted between pairs of complementing sheets and the assembly is subjected to elevated temperatures and pressures to bond the assembly together and form a unitary structure. During lamination, some portion of the interlayer material is squeezed out, i.e. extruded, from between the glass sheets about the windshield periphery. This material, or trim, must be removed to provide a clean, unobstructed edge about the periphery of the windshield.
The extruded interlayer material is typically removed using a razor blade or other sharp instrument. Using the edge of the windshield as a guide, the interlayer trim is removed from the windshield. It has been found that this procedure does not provide consistent edge quality and may chip one of the glass sheets of the windshield resulting in reduced edge strength.
It would be advantageous to provide a system that removes the extruded interlayer material in a consistently uniform manner without affecting the windshield edge strength.
2b. Patents of Interest
U.S. Pat. No. 2,926,371 to Swindler teaches an edge treating apparatus wherein a bent laminate is conveyed past a brushing tool that treats one edge of the moving laminate. Stops are provided along the opposite edge of the laminate to maintain the first edge against the brush. The stops and brush are mounted on an assembly that swings about a horizontal axis so that the brush and stops can receive and discharge the advancing laminate.
U.S. Pat. Nos. 2,579,337 and 2,597,180 to Reaser et al. teach a glass edge grinding machine. A flat glass sheet is rotated about a vertical axis and its edge is ground to a desired configuration by a grinding wheel.
U.S. Pat. No. 2,637,951 to White teaches the use of a belt driven edging tool. A plurality of belts are positioned diagonally relative to the edge of a glass sheet and the glass sheet is moved between the belts so that the belts contact opposing edges of the sheet. The belts flex between support rollers as the belts contact the glass edge to provide a uniformly ground edge along the opposing edges of the glass sheet, including the corners of the sheet.
U.S. Pat. No. 4,739,590 to Myers et al. teaches a method of seaming a glass sheet. The glass sheet advances in a linear direction between pairs of seaming heads to seam opposing edges of the glass. The glass is then rotated 90.degree. and the remaining opposing edges are seamed.